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Forces, tension in cable

  1. Oct 5, 2014 #1
    1. The problem statement, all variables and given/known data
    A huge Halloween decoration of mass 100kg is suspended by 3 cables. Each cable is exactly 25m long and is attached to each of the three building equidistant from each other. Each cable makes an angle of 30 degrees with the side of the building to which it is attached. What is the magnitude of the tension in each cable?

    2. Relevant equations
    fnet=ma

    3. The attempt at a solution
    vertical component for all cables= Tcos30
    fnet in y direction = 0
    fnet=0
    3(Tcos30)=Fg
    3Tcos30=100(9.81)
    T= 283.2N
     
  2. jcsd
  3. Oct 5, 2014 #2

    Orodruin

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    Looks reasonable apart from the numerical value you got in the end, what is your question? Did you multiply the RHS with cos30 instead of dividing when solving for T?
     
  4. Oct 5, 2014 #3
    oh ya sorry i made a mistake in calculations....but i still dont know if my answer is right. and what is the purpose for giving the length of the cable?
     
  5. Oct 6, 2014 #4

    Orodruin

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    They probably just wanted to make really really sure that you treated the problem as symmetric under 120 degree rotations.

    So what do you get now?
     
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